When a capacitor is provided in an electronic device, an electric charge is accumulated in the capacitor after an operation of the electronic device is finished. The accumulated electric charge needs to be discharged (for example, see Patent Literature 1). In the technology disclosed in Patent Literature 1, an electric motor generator consumes the residual electric charge of the capacitor by driving an inverter after notification of completion of a charge control.
Although the technology disclosed in Patent Literature 1 targets the discharge of the capacitor between a boost converter and the inverter, the capacitor exists even in a wireless power transfer system (see Patent Literature 2, for example). In the wireless power transfer system disclosed in Patent Literature 2, a smoothing capacitor is provided at an input of the inverter of the primary-side wireless power transfer device (power transmitter).